This investigation supplements earlier studies done by Dr. Mirth and coworkers to develop a fluoride releasing device (FRD) for inta-oral use. This investigation, which is still in progress, is assessing the safety and efficacy in eight monkeys (Macaca fascicularis) of a FRD designed to release 0.2 mg F daily for six months. Inspection of the data suggests that there has been marked elevation of fluoride levels in the dental plaque and saliva but not in the serum. No untoward local or systemic effects were observed.